More demand means more price isn't it?
Probably, if people are buying, this will likely make the mempool to be congested. But like I meant before, not only bitcoin transactions that makes the mempool to be congested, Ordinals and Inscriptions are part of it.
I know of bitcoin network being currently congested but can't say about the ethereum network if this congestion has extended to them or not
Ethereum network has been congested more than bitcoin mempool since years ago, but both are congested now.
in bitcoin we make use of transaction fee while in ither cryptocurrencies it's called gas fee,
There are many other coins that call it just transaction fee, but some like ethereum call it gas fee.